The paper describes the research aimed at reducing wall interference in wind tunnels at low supersonic velocities. The results of such wind tunnel tests are often affected by wave perturbations generated by the model and reflected from the test section walls. This research describes the methods that can effectively reduce the wave reflection from the wall. A numerical investigation is presented that includes a novel boundary condition that eliminates disadvantages of previously considered methods. The numerical study was conducted in the frame of electronic wind tunnel concept and ANSYS CFX software. The numerical investigation showed that the effect of shock wave reflection could be reduced using a new type of boundary condition that is a combination of perforated walls and a controlled boundary layer.

The principle of maximum pressure for subsonic stationary three-dimensional vortex flows of an ideal gas (author Sizykh G.B., 2018) is applied to verify the calculation method and its implementation on a specific computer technology. The four criteria for solution's verification are proposed. The method for obtaining flow parameters is based on solving of discrete analogs of the Navier --- Stokes system of equations on three-dimensional non-structured computational meshes. For example, there was consider the vortex tear-off flow around the fuselage of a helicopter with an empennage and landing gear at obviously insufficient computing resources. Conclusions of the feasibility of applying the author's criteria for evaluation of a particular calculation and for estimation of reliability of the results have been made.

This paper is dedicated to modelling of processes which take place in biotechnical system "Wearable artificial kidney" during peritoneal dialysis. Mathematical model describes dynamics of metabolite mass transfer through peritoneal membrane with further dialysate regeneration in extracorporeal regeneration unit. Model allows to predict dialysate volume dynamics in patient's peritoneal cavity and describes dynamics of osmotic agent concentration. The main theoretical results were compared with empirical laboratory and medical data. Presented mathematical model can be potentially used in wearable artificial kidney developing and design.

A wide scope of numerical investigations was carried out to design the test demonstrator of transonic wind tunnel with prospective boundaries, which allow implementing the wall interference reduction. The investigation highlights the developing of the controlled boundary layer concept application in windtunnel testing of well-known test model NACA CRM.

This work is devoted to mathematical modeling of spent dialysate regeneration by sorption. A method for mathematical modeling of sorption of such metabolites as creatinine and uric acid in the sorption columns of a wear able artificial kidney is suggested. The method was tested with different types of activated carbon used in sorption columns. The root-mean-square criterion did not exceed 630 μmol/L.

Traditional boundaries of transonic wind tunnels (perforated and slotted walls) have some disadvantages that do not allow to completely remove wall interference on all main aerodynamic characteristics. This article focuses on the results of implementation of new boundary condition based, in general, on the idea of jet boundaries. Authors examine the implementation of the controlled boundary layer on solid walls, which characteristics were artificially increased with the aim of near-wall spoiler grid mounted at the test section entrance. The analysis underlines significant decreasing of wall interference on all main aerodynamic characteristics, including lift coefficient and pitching moment coefficient. We conclude that realization of the controlled boundary layer might become simple and rather effective method of wall interference reduction.

Attempts toward miniaturization of apparatuses for artificial blood purification (artificial kidney) have been made in recent years. A portable artificial kidney apparatus can be based on hemodialysis and peritoneal dialysis apparatuses. Available foreign portable apparatuses for artificial blood purification are discussed in this work. The advantages and disadvantages of the apparatuses are discussed.

Wall interference effect remains one of the most important factors distorting the wind tunnel test results, especially for transonic flow regimes. Traditionally the wall influence is taken into account by means of the boundary interference corrections applied to the balance test data. Dependent on the used calculation method, corrections may be applied either to differential characteristics (e.g. pressure distribution) or integral parameters (typically, Mach number and the angle of attack). The last approach is used when the flow disturbances are not very intensive and the flow field around a model in the test section is similar to that in the infinite flow but at slightly different flow conditions. In the case when the interference is strong the flow over a model may not be realized in the infinite flow at any combination of its characteristics and the correctness of the boundary interference approach should be checked individually for each test. This problem is the most acute at transonic velocities, because the non-linear effects accompanying the local supersonic zones and the shock waves appearance make problematic the application of most of the traditional boundary correction methods. The second approach is the so-called “adaptive-wall wind tunnels”. This concept implies that the boundary conditions during the test may be changed in such a way that the wall interference will be removed or at least considerably diminished [13]. The adaptive-wall concept is based on the well-known characteristic: distribution of the normal velocity component on the incompressible flow boundary fully defines the flow field inside it. Consequently, if the normal velocity distribution over the near-wall control surface becomes the same, as in the infinite flow, the wall interference will be eliminated. Practical implementation of this idea encounters a set of difficulties. First of all, it is difficult to predict precisely the normal velocity component distribution in the total transonic velocity range where interference is maximal. The iteration procedure of Sears [3] seems to be the most relevant for this case. One of the parameters (e.g. tangential velocity component u) serves as a boundary condition for calculation of the virtual external flow field. The result of this calculation is the definition of the second parameter (in this case – the normal velocity component v). Comparison of the calculated and measured distributions of v serves as the criterion of proximity of the boundary conditions to the interference-free ones. The advantage of such approach is the relative simplicity of the far field calculation, free from any viscous transonic effects prediction near the model surface and using the turbulence models. CONTROLLED BOUNDARY LAYER ON THE SOLID WALLS OF WIND TUNNELS: NEW APPROACH TO THE BOUNDARY INTERFERENCE PROBLEM